The present invention generally relates to materials science research, and specifically, to combinatorial (i.e., high throughput) materials science research directed toward the identification and/or optimization of new materials. The invention particularly relates, in preferred embodiments, to apparatus and methods for optimizing chemical reaction systems, such as chemical reaction systems involving heterogeneous catalysts.
In recent years, significant efforts have been extended toward developing parallel systems, such as parallel reactors, for the purpose of screening different materials, such as heterogeneous catalysts, for particular properties of interest, such as catalysis. U.S. Pat. No. 5,985,356 to Schultz et al. discloses synthesis and screening arrays of materials in parallel for catalysis, and U.S. Pat. No. 6,063,633 to Willson discloses parallel flow reactors, and parallel screening techniques (e.g., thermography, chromatography, etc.) for evaluating catalysis. A substantial portion of such effort has, however, focussed on apparatus and methods for evaluating compositional space of the materials (e.g., heterogeneous catalysts) of interest, while only a relatively small portion of such effort has been directed toward apparatus and methods for evaluating other parameter spaces—in addition to compositional space. More specifically for example, in the context of heterogeneous catalysis research, only limited attention has been focused on the development of apparatus and methods for high-throughput, parallel optimization of important parameters such as catalyst (or catalyst precursor) processing conditions and reaction conditions.
A number of parallel flow reactors are known in the art. For example, PCT application WO 98/07206 (Hoechst) discloses a parallel flow reactor said to be useful for evaluating chemical reactions using minaturized reactors, but does not address important considerations such as distribution systems for simultaneously delivering reactants to large numbers of flow reactors. U.S. Pat. No. 6,149,882 to Guan et al. discloses, among other facets, a parallel flow reactor for screening of heterogeneous catalysts in which feed flow is controlled using flow restrictors such as capillaries to obtain substantially the same flow in each of the reaction channels. WO 97/32208 (Technology Licensing Co., Ltd.) and DE 19809477 (Schuth) also contemplate parallel flow reactors having uniform flow through each of the reaction channels. WO 99/41005 (BASF) and DE 19806848 (BASF) disclose parallel flow reactor configurations as well. These and other reactor designs known in the art do not, however, specifically address approaches or contemplate apparatus for investigating and/or optimizing process conditions simultaneously in large numbers of reactors. More recently, WO 00/51720 (Symyx Technologies, Inc.) discloses a parallel flow reactor design that addresses several significant technical challenges, including flow distribution challenges for parallel screening of catalysts in very large numbers.
Although controlling reaction conditions is well known for single reaction systems, or even for larger scale (e.g. production scale and/or pilot plant scale) applications, existing approaches would not be well-suited for parallel reaction systems, due to differences in reactor scale and associated effects on reaction parameters (e.g., on mass transfer and/or heat transfer), or due to expense (e.g. of conventional mass flow controllers). Known reactors or microreactors also have common limitations, for example, with respect to a low throughput (e.g., the number of catalysts that can be screened over a given period of time), a narrow distribution of heterogeneous catalyst contact times, a large amount of each (often expensive) candidate catalyst required to effect the chemical conversion, the potential inherent negative influence of microreactor materials on a reaction of interest, a high degree of complexity, a lack of flexibility for analyzing the results of the chemical conversion, in some cases, a lack of scalability of research results to production-scale systems, and a large spatial footprint.
Hence, there remains a need in the art to overcome such deficiencies, and to provide for parallel flow reactors having robust operational capabilities to systematically investigate and/or optimize chemical process conditions such as reaction conditions for a chemical reaction of interest. Significant advances were achieved, in this regard, more recently by Bergh et al., who disclosed in WO 00/51720 (Symyx Technologies, Inc.) a parallel flow reactor design that addresses several of such technical challenges, including flow distribution challenges for parallel screening of catalysts in very large numbers, and for evaluation of process conditions in a parallel flow reactor. The present invention builds on, and offers substantial advances over this most recent work.